Fertilizers - Determination of urea condensates using high-performance liquid chromatography (HPLC) - Isobutylidenediurea and crotonylidenediurea (method A) and methylene-urea oligomers (method B) (ISO 25705:2016)

ISO 25705:2016 specifies methods for the determination of isobutylidene diurea (IBDU), Crotonylidene diurea (CDU) (method A) and methylene-urea oligomers (MU) (method B) in fertilizers using high-performance liquid chromatography (HPLC).
The method is applicable to all fertilizers which do not contain interfering organic compounds.

Düngemittel - Bestimmung von Harnstoffkondensaten mit Hochleistungs-Flüssigchromatographie (HPLC) - Isobutylidendiharnstoff und Crotonylidendiharnstoff (Verfahren A) und Methylenharnstoff-Oligomere (Verfahren B)

Engrais - Dosage des condensats d'urée par chromatographie liquide haute performance (HPLC) - Isobutylidène diurée et crotonylidène diurée (méthode A) et oligomères de méthylène-urée (méthode B) (ISO 25705:2016)

La présente Norme internationale spécifie les méthodes de dosage de l'isobutylidène diurée (IBDU), de la crotonylidène diurée (CDU) (méthode A) et des oligomères de méthylène-urée (MU) (méthode B) dans les engrais par chromatographie liquide haute performance (HPLC).
La méthode est applicable à tous les engrais qui ne contiennent pas de composés organiques interférents.

Gnojila - Določevanje kondenzatov sečnine s tekočinsko kromatografijo visoke ločljivosti (HPLC) - Izobutilidendiurea in krotonilidendiurea (metoda A) in oligomeri metilenuree (metoda B) (ISO 25705:2016)

General Information

Status
Not Published
Public Enquiry End Date
03-Jul-2019
Technical Committee
Current Stage
98 - Abandoned project (Adopted Project)
Start Date
20-Aug-2020
Due Date
25-Aug-2020
Completion Date
20-Aug-2020

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SLOVENSKI STANDARD
oSIST prEN ISO 25705:2019
01-junij-2019
Gnojila - Določevanje kondenzatov sečnine s tekočinsko kromatografijo visoke

ločljivosti (HPLC) - Izobutilidendiurea in krotonilidendiurea (metoda A) in oligomeri

metilenuree (metoda B) (ISO 25705:2016)
Fertilizers - Determination of urea condensates using high-performance liquid

chromatography (HPLC) - Isobutylidenediurea and crotonylidenediurea (method A) and

methylene-urea oligomers (method B) (ISO 25705:2016)
Düngemittel - Bestimmung von Harnstoffkondensaten mit Hochleistungs-

Flüssigchromatographie (HPLC) - Isobutylidendiharnstoff und Crotonylidendiharnstoff

(Verfahren A) und Methylenharnstoff-Oligomere (Verfahren B); Deutsche und Englische

Fassung prEN ISO 25705:2018
Engrais - Dosage des condensats d'urée par chromatographie liquide haute
performance (HPLC) - Isobutylidène diurée et crotonylidène diurée (méthode A) et
oligomères de méthylène-urée (méthode B) (ISO 25705:2016)
Ta slovenski standard je istoveten z: prEN ISO 25705
ICS:
65.080 Gnojila Fertilizers
71.040.50 Fizikalnokemijske analitske Physicochemical methods of
metode analysis
oSIST prEN ISO 25705:2019 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN ISO 25705:2019
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oSIST prEN ISO 25705:2019
INTERNATIONAL ISO
STANDARD 25705
First edition
2016-04-01
Fertilizers — Determination of
urea condensates using high-
performance liquid chromatography
(HPLC) — Isobutylidenediurea and
crotonylidenediurea (method A) and
methylen-urea oligomers (method B)
Engrais — Dosage des condensats d’urée par chromatographie
liquide haute performance (CLHP) — Isobutylidène diurée et
crotonylidène diurée (méthode A) et oligomères de méthylène-urée
(méthode B)
Reference number
ISO 25705:2016(E)
ISO 2016
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oSIST prEN ISO 25705:2019
ISO 25705:2016(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2016, Published in Switzerland

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form

or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior

written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of

the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2016 – All rights reserved
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oSIST prEN ISO 25705:2019
ISO 25705:2016(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Sampling and sample preparation .................................................................................................................................................... 1

5 Method A: Determination of CDU and IBDU ............................................................................................................................. 1

5.1 Principle ........................................................................................................................................................................................................ 1

5.2 Reagents........................................................................................................................................................................................................ 1

5.3 Apparatus .................................................................................................................................................................................................... 2

5.4 Procedure .................................................................................................................................................................................................... 2

5.4.1 System parameters of HPLC ................................................................................................................................... 2

5.4.2 Calibration ............................................................................................................................................................................. 2

5.4.3 Preparation of the test portion ............................................................................................................................ 3

5.4.4 Measurement ...................................................................................................................................................................... 3

5.4.5 Important annotations ............................................................................................................................................... 3

5.5 Calculation .................................................................................................................................................................................................. 3

6 Method B: Determination of methylene-urea oligomers (MU) ............................................................................ 4

6.1 Principle ........................................................................................................................................................................................................ 4

6.2 Reagents........................................................................................................................................................................................................ 4

6.3 Apparatus .................................................................................................................................................................................................... 4

6.4 Procedure .................................................................................................................................................................................................... 5

6.4.1 System parameters of HPLC ................................................................................................................................... 5

6.4.2 Calibration ............................................................................................................................................................................. 5

6.4.3 Preparation of the test solution .......................................................................................................................... 6

6.4.4 Measurement ...................................................................................................................................................................... 7

6.4.5 Important annotations ............................................................................................................................................... 7

6.5 Calculations ................................................................................................................................................................................................ 7

7 Precision method A and method B .................................................................................................................................................... 8

7.1 Inter-laboratory test........................................................................................................................................................................... 8

7.2 Repeatability ............................................................................................................................................................................................. 8

7.3 Reproducibility ....................................................................................................................................................................................... 8

8 Test report ................................................................................................................................................................................................................... 9

Annex A (informative) Results of the inter-laboratory tests ....................................................................................................10

Annex B (informative) Chromatogram and calibration curves method A ..................................................................12

Annex C (informative) Chromatogram and calibration curves method B...................................................................14

Bibliography .............................................................................................................................................................................................................................17

© ISO 2016 – All rights reserved iii
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oSIST prEN ISO 25705:2019
ISO 25705:2016(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www.iso.org/patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation on the meaning of ISO specific terms and expressions related to conformity

assessment, as well as information about ISO’s adherence to the WTO principles in the Technical

Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information

ISO 25705 was prepared by CEN/TC 260 (as EN 15705:2010) and was adopted by Technical Committee

ISO/TC 134, Fertilizers and soil conditioners. The following modifications were made.

— The references to EN 1482-1 and EN 1482-2 were changed to ISO 14820-1 and ISO 14820-2.

— In 5.2.1 and 6.2.1, the general text (not related to the water) was moved directly under 5.2 and 6.2,

respectively.

— In Table 1, the word “approximate” was added to the column headers for IBDU and CDU.

— In 5.4.3 and 6.4.3, “the sample grounded” was changed to “the ground sample”.
— In 6.4.3, “pieces of glass” and “pieces” were replaced by “boiling stones”.

— In 6.4.2.1, 6.4.2.2, 6.4.2.3, and 6.4.2.4, “by placing the flask in the” was added before “ultrasonic bath”.

— In 6.4.2.1, 6.4.2.2, 6.4.2.3, 6.4.2.4, 6.4.2.5 and 6.4.3, “homogenize” was changed to “mix thoroughly”.

— In 6.4.2.5, “before transferring into” was changed to “before transferring in” three times.

— In the keys for Figures B.2, B.3, B.4, C.2, C.3, C.4 and C.5, the units for the areas were added.

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oSIST prEN ISO 25705:2019
ISO 25705:2016(E)
Introduction

Fertilizers containing the condensates of urea and specified aldehydes (with crotonaldehyde called

crotonyliden diurea or CDU, with isobutyraldehyde called isobutylidene diurea or IBDU, with

formaldehyde called urea formaldehyde or methylene urea or MU) are covered by Regulation (EC)

[4]

2003/2003, Annex I as nitrogenous fertilizers. The methods described in this International Standard

enable the quantitative determination of these condensates and the determination of the solubility of

the MU-oligomers according to the Regulation.
© ISO 2016 – All rights reserved v
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oSIST prEN ISO 25705:2019
INTERNATIONAL STANDARD ISO 25705:2016(E)
Fertilizers — Determination of urea condensates using
high-performance liquid chromatography (HPLC) —
Isobutylidenediurea and crotonylidenediurea (method A)
and methylen-urea oligomers (method B)
1 Scope

This International Standard specifies methods for the determination of isobutylidene diurea (IBDU),

Crotonylidene diurea (CDU) (method A) and methylene-urea oligomers (MU) (method B) in fertilizers

using high-performance liquid chromatography (HPLC).

The method is applicable to all fertilizers which do not contain interfering organic compounds.

2 Normative references

The following documents, in whole or in part, are normatively referenced in this document and are

indispensable for its application. For dated references, only the edition cited applies. For undated

references, the latest edition of the referenced document (including any amendments) applies.

ISO 3696, Water for analytical laboratory use — Specification and test methods

ISO 14820-2, Fertilizers and liming materials — Sampling and sample preparation — Part 2: Sample

preparation

EN 12944-1, Fertilizers and liming materials and soil improvers — Vocabulary — Part 1: General terms

EN 12944-2, Fertilizers and liming materials and soil improvers — Vocabulary — Part 2: Terms relating to

fertilizers
3 Terms and definitions

For the purposes of this document, the terms and definitions given in EN 12944-1 and EN 12944-2 apply.

4 Sampling and sample preparation

Sampling is not part of the method specified in this International Standard. A recommended sampling

method is given in ISO 14820-1.
Sample preparation shall be carried out in accordance with ISO 14820-2.
5 Method A: Determination of CDU and IBDU
5.1 Principle

The sample is extracted with water and, after appropriate dilution, analysed using a suitable HPLC system.

5.2 Reagents
Use only reagents of recognized analytical grade, unless otherwise specified.
5.2.1 Water, distilled or demineralized water (grade 3 according to ISO 3696).
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ISO 25705:2016(E)
5.2.2 Acetonitrile, HPLC-grade.
5.2.3 Isobutylidene diurea and Crotonylidene diurea, in their pure form.
5.3 Apparatus

5.3.1 Laboratory equipment and glassware, for preparation of solutions and dilutions.

5.3.2 Analytical balance, capable of weighing to an accuracy of ±0,1 mg.
5.3.3 HPLC-system, with UV-detector.
5.3.4 Ultrasonic bath.
5.3.5 Magnetic stirrer.
5.3.6 Disposable filter, 0,45 μm.
5.4 Procedure
5.4.1 System parameters of HPLC
Analytical/separating column: silica column with C18 reverse phase
Detection wavelength: 200 nm
Eluent: acetonitrile/water: 10/90 (volume fraction)
Flow rate: 1 ml/min
Temperature: ambient temperature
Injection volume: 20 μl
5.4.2 Calibration
5.4.2.1 Stock solution IBDU ρ(IBDU) = 100 mg/l

Weigh 100/R mg of IBDU (5.2.3), where R is the purity of IBDU, into a 1 000 ml flask and add about

900 ml of water (5.2.1). Dissolve in an ultrasonic bath (5.3.4) for about 10 min, followed by stirring on a

magnetic stirrer (5.3.5) for about 1 h. Make up to volume. Filtration is not necessary.

5.4.2.2 Stock solution CDU ρ(CDU) = 100 mg/l

Weigh 100/R mg of CDU (5.2.3), where R is the purity of CDU, into a 1 000 ml flask and add about

900 ml of water (5.2.1). Dissolve in an ultrasonic bath (5.3.4) for about 10 min, followed by stirring on a

magnetic stirrer (5.3.5) for about 1 h. Make up to volume. Filtration is not necessary.

5.4.2.3 Calibration solution

For calibration, prepare three solutions according to Table 1 using one-mark (bulb) pipettes and dilute

to the mark with water (5.2.1).

1) LiChrosorb RP-18 7 µm 250/4 mm is an example of a suitable product available commercially. This information

is given for the convenience of users of this International Standard and does not constitute an endorsement by ISO

of this product.
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ISO 25705:2016(E)

For the determination of the retention time, dilute 10 ml of the stock solution (5.4.2.1) or respectively

(5.4.2.2) into two 100 ml flasks and make up to volume with water (5.2.1).

The evaluation of calibration is carried out manually or by means of a suitable PC-aided (computerized)

calculation method.
Table 1 — Preparation of calibration solutions
Parameter Amount of stock Content of IBDU Content of CDU
solution IBDU/CDU mg/l mg/l
(approximate) (approximate)
(to be added to the
100 ml flask)
Standard 1 10 10,0 10,0
Standard 2 25 25,0 25,0
Standard 3 50 50,0 50,0
5.4.3 Preparation of the test portion

Weigh 1 g of the ground sample to <0,2 mm to the nearest 0,1 mg and quantitatively transfer into a

1 000 ml volumetric flask with water (5.2.1). Fill the flask to an amount of approximately 900 ml and

treat it for 10 min in the ultrasonic bath (5.3.4). Then make up to the mark and stir for 1 h at room

temperature on a magnetic stirrer (5.3.5). Dilute 10 ml of the solution in a 100 ml volumetric flask and

filter into the HPLC injection vial through a disposable filter (5.3.6).
5.4.4 Measurement

Measurement is performed manually or by means of an automatic sample loading system (autosampler).

5.4.5 Important annotations

IBDU is able to form urea in aqueous solution. Therefore, the measurement of the calibration and sample

solutions shall be completed within one working day.

The concentrations of CDU and IBDU in the sample solutions shall be kept within the calibration limits

(5.4.2) to ensure sufficient reproducibility.
5.5 Calculation

The calculation can be performed manually or by means of a PC using the calibration parameters in

respect to the amount used.

In the case of PC-aided (computerized) calculation and application of Table 1 regarding the amounts of

stock solution, the
...

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